--- /dev/null
+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+ This file is part of systemd.
+
+ Copyright 2014 Zbigniew Jędrzejewski-Szmek
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd_bus_new">
+
+ <refentryinfo>
+ <title>sd_bus_new</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>A monkey with a typewriter</contrib>
+ <firstname>Zbigniew</firstname>
+ <surname>Jędrzejewski-Szmek</surname>
+ <email>zbyszek@in.waw.pl</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>sd_bus_new</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_bus_new</refname>
+ <refname>sd_bus_ref</refname>
+ <refname>sd_bus_unref</refname>
+ <refname>sd_bus_unrefp</refname>
+
+ <refpurpose>Create a new bus object and create or destroy references to it</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_bus_new</function></funcdef>
+ <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>sd_bus *<function>sd_bus_ref</function></funcdef>
+ <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>sd_bus *<function>sd_bus_unref</function></funcdef>
+ <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>void <function>sd_bus_unrefp</function></funcdef>
+ <paramdef>sd_bus **<parameter>bus</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><function>sd_bus_new()</function> creates a new bus
+ object. This object is reference-counted, and will be destroyed
+ when all references are gone. Initially, the caller of this
+ function owns the sole reference and the bus object will not be
+ connected to any bus. To connect it to a bus, make sure
+ to set an address with
+ <citerefentry><refentrytitle>sd_bus_set_address</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ or a related call, and then start the connection with
+ <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+ <para>In most cases, it is a better idea to invoke
+ <citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ or related calls instead of the more low-level
+ <function>sd_bus_new()</function> and
+ <function>sd_bus_start()</function>. The higher-level calls not
+ only allocate a bus object but also start the connection to a
+ well-known bus in a single function invocation.</para>
+
+ <para><function>sd_bus_ref()</function> increases the reference
+ counter of <parameter>bus</parameter> by one.</para>
+
+ <para><function>sd_bus_unref()</function> decreases the reference
+ counter of <parameter>bus</parameter> by one. Once the reference
+ count has dropped to zero, <parameter>bus</parameter> is destroyed
+ and cannot be used anymore, so further calls to
+ <function>sd_bus_ref()</function> or
+ <function>sd_bus_unref()</function> are illegal.</para>
+
+ <para><function>sd_bus_unrefp()</function> is similar to
+ <function>sd_bus_unref()</function> but takes a pointer to a
+ pointer to an <type>sd_bus</type> object. This call is useful in
+ conjunction with GCC's and LLVM's <ulink
+ url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
+ Variable Attribute</ulink>. Note that this function is defined as
+ inline function. Use a declaration like the following, in order to
+ allocate a bus object that is freed automatically as the code
+ block is left:</para>
+
+ <programlisting>{
+ __attribute__((cleanup(sd_bus_unrefp)) sd_bus *bus = NULL;
+ int r;
+ …
+ r = sd_bus_default(&bus);
+ if (r < 0)
+ fprintf(stderr, "Failed to allocate bus: %s\n", strerror(-r));
+ …
+}</programlisting>
+
+ <para><function>sd_bus_ref()</function>,
+ <function>sd_bus_unref()</function> and
+ <function>sd_bus_unrefp()</function> execute no operation if the
+ passed in bus object is <constant>NULL</constant>.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para>On success, <function>sd_bus_new()</function> returns 0 or a
+ positive integer. On failure, it returns a negative errno-style
+ error code.</para>
+
+ <para><function>sd_bus_ref()</function> always returns the argument.
+ </para>
+
+ <para><function>sd_bus_unref()</function> always returns
+ <constant>NULL</constant>.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Errors</title>
+
+ <para>Returned errors may indicate the following problems:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><constant>-ENOMEM</constant></term>
+
+ <listitem><para>Memory allocation failed.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para><function>sd_bus_new()</function> and other functions
+ described here are available as a shared library, which can be
+ compiled and linked to with the
+ <constant>libelogind</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ file.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_open_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_bus_open_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>
~ianmdlvl / elogind.git / blobdiff